Wet Grip Research Articles

ISO test track influence on the EU tyre label noise value

In 2009, the European Union (EU) introduced a directive governing the labelling of tyres, which underwent revision in 2020. This labelling system encompasses three key parameters related to tyre performance: wet grip (safety), rolling resistance (energy consumption), and external rolling noise (environmental impact). These label values serve as crucial information for customers seeking to purchase replacement tyres for their vehicles.However, the accuracy and reliability of noise measurements have been a concern. Testing conducted across various ISO-standardized tracks has revealed significant inconsistencies in noise levels, with variations of 4–5 dB between tracks. Such discrepancies directly impact the labelling process, introducing uncertainty.This paper presents results of tyre noise measurements conducted on a limited number of ISO test tracks and proposes a methodology to mitigate track-to-track variability. The study exclusively focuses on passenger car tyres. By addressing these inconsistencies, this research aims to enhance the accuracy and reliability of tyre noise labelling, thereby facilitating informed consumer decision-making and promoting environmental sustainability.

The effect of silane‐modified carbon black and nano‐silica, individually and in combination, on the performance of ethylene–propylene–diene monomer rubber

AbstractThis study assesses the effectiveness of a specially developed surface‐modified carbon black, both on its own and in combination with nano‐silica, as a hybrid filler for ethylene–propylene–diene monomer (EPDM) rubber compounds. The modification process, which included treatment with a silane coupling agent, resulted in enhanced curing characteristics. The ∆Torque values for compounds incorporating the modified carbon black exceeded those of other formulations by 25.85%. Scanning electron microscopy (SEM) analysis demonstrated improved filler dispersion and better compatibility between rubber and filler due to the surface modification. The silane‐modified carbon black showed considerable enhancements in mechanical properties, particularly in tear resistance, with increases in tensile and tear strength of 22.46% and 34.86%, respectively, following surface treatment. Dynamic mechanical analysis (DMA) indicated the influence of both surface modification and filler type, revealing that the combination of modified carbon black and nano‐silica achieved a reduction in rolling resistance of 20.41% and enhanced ice and wet grip performance by 7.95%. Additionally, modified carbon black displayed varying effects on the glass transition temperature. Thermal gravimetric analysis (TGA) confirmed that the thermal stability of the compounds was consistent, while solvent resistance improved with surface modification, as shown by swelling ratios. Thermodynamic analysis indicated that the surface modification of carbon black positively influences the elasticity and chain mobility of the rubber compounds studied. In conclusion, the careful selection and optimization of filler materials and their modifications are essential for customizing the properties of rubber compounds to satisfy specific performance criteria and applications.Highlights Promising EPDM compounds were prepared with Silane‐Modified CB and Nano‐Silica. Silane‐modified CB effectively improved the curing properties of the EPDM compound. The ΔTorque and cross‐link density of modified CB/EPDM show the highest value. Modified CB/Nano‐Silica/EPDM exhibited significant improvement in tear strength. Modified CB/Nano‐silica/EPDM have lower rolling resistance and higher wet grip.

Graphene Oxide-Silica Green Hybrid Nanocomposites: Fabrication via Latex Mixing and Mechanical Properties Evaluation

ABSTRACT This study investigates the incorporation of sustainable self-assembled graphene oxide-nano silica (GO/NS) hybrid nanoparticles into the natural rubber latex matrix via latex mixing. The primary objective is to assess the synergistic impact of these nanofillers on the mechanical properties of natural rubber latex using both static and dynamic mechanical analysis. Results reveal significant enhancements in mechanical properties, with NRL GO/NS 2 exhibiting a remarkable 188% increase in tensile strength and NRL GO/NS 3 showing a substantial 107% increase. Furthermore, NRL GO/NS 3 demonstrates a 30% reduction in rolling resistance and a remarkable 200% improvement in wet grip, while NRL GO/NS 2 exhibits an 88% increase in wet grip and a 43% decrease in rolling resistance, suggesting potential fuel efficiency benefits. These advancements hold promise for various applications such as automotive tire manufacturing, biomedical devices, and the production of elastomeric goods.

Effect of demineralized water on the silanization reaction and the performance properties of green tire tread compound

AbstractTire industries seek advancements in technologies ranging from novel constructions to new material systems for fuel efficiency. The chemical formulation of tread compounds and their processing conditions can significantly affect tire performance for key attributes, including rolling resistance, wet traction, and wear resistance. Adding demineralized water (DMW) molecules might enhance the silanization reaction between silane and silica filler surface via improved hydrolysis and condensation, resulting in a better silanization reaction. DMW was sprayed on a silica surface before mixing, incorporated with TESPD silane into S‐SBR/BR tire tread compound, and mixed in an internal mixer. The effects of an increase in the DMW content on compound processability, cure characteristics, filler dispersion, dynamic properties, and mechanical properties were investigated. Adding the water‐treated silica into the compound lowered the heat generation during mixing, lowered the dump temperature, lowered the tan δ (E″/E′) at 60°C, and increased the wet grip property by retaining the abrasion resistance compared with the control. The enhancement of filler dispersion was visualized via scanning electron microscope images. Reaction kinetics concerning the addition of water and the effect of the pH of water on the silanization reaction is also discussed using HPLC analysis.

Synergistic effects of silane‐modified carbon black and nano‐silica hybrid fillers on the performance of natural rubber compounds

AbstractThis study investigates the efficiency of already developed surface‐modified carbon black (CB), both independently and in conjunction with nano‐silica, as a hybrid filler, to the properties of natural rubber (NR) compounds. The modification process, followed by coupling agent treatment, enhanced cross‐link density and curing characteristics, though the inclusion of nano‐silica alone negatively affected curing due to its inherent polarity and tendency to agglomerate. The filled compounds with modified CB exhibited significant improvements in mechanical properties, notably tear resistance. Moreover, the combination of nano‐silica with modified CB yielded compounds with superior tear resistance, attributed to synergistic effects. CB surface modification exhibited varying effects on the glass transition temperature, with enhancements observed in tan δ at lower temperatures, indicating improved ice and wet grip potential. Also, it reduced rolling resistance after treatment with a coupling agent. While thermal stability remained consistent across the studied compounds, swelling resistance varies with filler type and ratio. Thermodynamic analysis confirmed the positive impact of CB surface modification on the elasticity and chain mobility of the investigated rubber compounds. It was concluded that the strategic selection of fillers and modification approaches were essential for achieving optimal results in the rubber compound's performance and application.

COMPATIBILITY STUDY OF HYDROCARBON RESINS WITH RUBBER COMPOUNDS FOR TIRE APPLICATIONS

ABSTRACT The addition of hydrocarbon resins to rubber compounds has a significant impact on their properties such as wet grip and rolling resistance. These performance characteristics have a strong correlation with the compatibility of the resin with the rubber matrix. Incompatible resins can cause excessive broadening of the damping curve, which results in poor rolling resistance. Compatibility, however, allows maximization of wet grip while minimizing the effect on rolling resistance. Compatibility is promoted by lower resin molecular weight and structural similarity to the polymers being blended. In this study, a method based on the Fox equation has been developed to quantitatively characterize the compatibility between resin and natural rubber (NR), a binary system. The dynamic shear rheometer (DSR), a tool new to the tire industry, is used to investigate the interaction between resin and two rubbers (i.e., a ternary system of NR–butadiene rubber [BR]–resin and solution polymerized styrene–butadiene rubber [SSBR]–butadiene rubber [BR]–resin), with a specific emphasis on resin partitioning among rubber blends. In addition, the DSR is applied to assess the Tg shift and tangent delta peak height, providing insight into the compatibility between rubbers and resin. A curve-fitting model was developed for the SSBR–BR–resin system to depict the relationship between these two parameters and the physical and chemical properties of resins, with the selection of resins featuring different degrees of aromaticity, Tg, and molecular weight. The findings indicated that higher Tg increased aromaticity and that lower molecular weight of the resin resulted in an elevated Tg shift in the blend, while lower molecular weight led to an increase in the tangent delta peak height. Our findings supply insight into the performance of rubber–resin blends and introduce a new screening tool for characterizing these blends in their green state.

Heading towards a fully sustainable tire tread compound: use of bio-based resins

The automotive industry is in constant development, with a special focus on increasing the sustainability of tires while maintaining their high performance. One of the most used approaches to reach this goal is the use of bio-based raw materials. On this basis, this work aims to substitute the traditional plasticizers used in tire tread compounds (obtained from non-renewable resources) by bio-based resins. These materials can function as plasticizers in rubber compounds and in contrast with vegetable oils, they are not in conflict with the food industry. With this purpose, four different bio-based resins with different properties were analyzed. The effect of these resins on the in-rubber properties was studied in a silica-filled styrene butadiene rubber (SBR)/polybutadiene rubber (BR) compound. The use of these natural products resulted in similar or improved mechanical properties, higher crosslink density, improved dispersion and higher wet grip indicator compared to a TDAE-based compound. However, the addition of the resins also led to a deterioration in the abrasion resistance and the rolling resistance indicator.

Investigation of the effect of silica particles and silane coupling agent on silica-filled tire tread compounds

Enhancing attributes such as abrasion resistance, wet grip, and rolling resistance significantly impacts the overall performance optimization in tire tread applications. These attributes are predominantly influenced by the dispersity of silica filler within tire tread compounds. Therefore, it becomes imperative to enhance silica dispersion by thoroughly investigating the impact of each constituent in the tire tread compound. This study aims to elucidate the effects of silica particle size and silane coupling agents on tire tread compound properties. The results demonstrate that larger specific surface area silica particles alongside 3-mercaptopropyltrimethoxysilane coupling agents effectively reduce filler–filler interactions and enhance silica dispersion within the tire tread compound. Consequently, these improvements contribute to the overall enhancement of tire tread compound performance. These findings offer valuable insights into advancing the reinforced performance of tire tread compounds through the synergistic utilization of each constituent.

Synergistic effect of Tween 20 and TESPT compatibilizers on the performance characteristics of latex imprinted silica-reinforced green tyre tread formulation

The present study has a prime goal to develop a green tyre tread formulation with enhanced performance characteristics including low rolling resistance, improved wet grip, low heat build-up and enhanced mechanical properties which are essential for a high-performance tyre tread compound. A base formulation of natural rubber/polybutadiene (NR/BR) blend with minimum carbon filler was formulated initially without compromising the physical properties much by balancing the properties by incorporating precipitated silica. Enhanced surface area for silica was obtained through the latex imprinting method which had an ultimate effect on the interaction between the matrix macromolecules and filler particles positively. Further, ENR was used as a compatibilizing agent to upgrade physical properties in terms of 20% improvement in tensile and around 10% improvement in tear strength. Additional improvement in physical as well as rolling resistance performance was achieved via the incorporation of coupling agents including TESPT and polyoxyethylene(20) sorbitan monolaurate (Tween 20). Apart from the improvement in mechanical properties, rolling resistance and heat build-up properties are promising for the final tyre tread formulation as both the values tend to reduce considerably by 35% and 63% respectively concerning the base formulation.

The Influence of Styrene Content in Solution Styrene Butadiene Rubber on Silica-Filled Tire Tread Compounds

In tire tread applications, achieving enhanced abrasion resistance, wet grip, and rolling resistance is crucial for optimizing overall performance. To realize improvements in these attributes for silica-filled tire tread compounds, it becomes imperative to improve the dispersity of silica filler by investigating the effect of each component in the tire tread compound. In this work, we study the effect of styrene content within solution styrene butadiene rubber (SSBR) on the properties of tire tread compounds. A higher styrene segment within SSBR contributes to increased silica dispersion and crosslink density. Thus, tire tread compounds featuring SSBR with increased styrene content not only improve physical and mechanical properties, but also enhance major characteristics tailored for tire tread applications. These findings provide valuable insights into advancing the reinforced performance of tire tread compounds through the strategic utilization of SSBR enriched in styrene content.

Preparation and properties of rice husk ash silica filled natural rubber

AbstractRice husk ash silica obtained from the chemical purification of rice husk ash is a bio‐based silica. As a sustainable raw material, the bio‐based silica has attracted much attention in recent years. It can be used to replace traditional carbon black and silica in tire rubbers. Our experimental results show that the bio‐based silica can bring similar mechanical properties and higher wet grip to natural rubber in comparison with traditional silica. The wet mixing method is successfully used to disperse the bio‐based silica in natural rubber latex, obtaining a bio‐based silica/natural rubber composite with higher abrasion resistance and lower rolling resistance than the composite prepared by traditional dry mixing. The mechanical properties of bio‐based silica/natural rubber composites depend on the silica loading and mixing methods. Mixing natural rubber and bio‐based silica through wet‐mixing method is a green and sustainable approach to the tread rubbers with excellent mechanical properties, low rolling resistance, high abrasion resistance, and wet grip.

Utilization of biosilica for energy-saving tire compounds: Enhancing performance and efficiency

Abstract Energy-saving tires have been developed by researchers in the industry in order to minimize hysteresis loss. In general, this is achieved by combining precipitated silica sourced from silica sand with a silane coupling agent. This strategic reaction serves to elevate the performance characteristics of tread tire, effectively enhancing their properties. Therefore, this research is aimed to investigate the utilization of commercially available biosilica compared to high dispersed (HD) silica, examining their potential as reinforcing agents in the composition of passenger tread tire compound. This compound was formulated using a blend of solution styrene-butadiene rubber (SSBR) and butadiene rubber (BR). A comprehensive analysis was conducted to assess the impact of varying ratios between biosilica and HD silica on the mechanical and dynamic properties of tread tire compound composed of SSBR and BR blend. The results showed that the incorporation of biosilica could effectively reduce the filler network resulting in better dispersion of biosilica in the SSBR/BR blend matrix. As a result, it improved wet grip (44%) and rolling resistance (26%) while maintaining abrasion resistance compared with HD silica in passenger tread tire compound. The application of biosilica as an eco-friendly reinforcement material exhibited its potential for elevating the performance of energy-efficient tread tire.

Synthesis of sonochemical chloroacetated natural rubber and its potential use in passenger car tire tread

This article describes the preparation of chloroacetated natural rubber (CNR) through the epoxidation of natural rubber (NR) latex with performic acid, followed by the reaction with chloroacetic acid. Ultrasound waves were utilized to accelerate the epoxidation reaction. The CNR samples obtained at various epoxidation durations were analyzed by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, and differential scanning calorimetry techniques. Results showed that the chloroacetate content in CNR increased with increasing epoxidation time, i.e., the chloroacetate contents were 17.4, 18.5, and 19.7% at epoxidation times of 30, 45, and 60 min, respectively. The prepared CNR samples were then employed to replace NR in silica-filled tire tread compounds based on a 70/30 solution styrene butadiene rubber (SSBR)/NR blend. It was found that, compared with NR, CNR provided significantly higher rubber-silica interaction, leading to improved mechanical and dynamic properties. Such replacement not only reduced heat build-up and rolling resistance, but also increased the wet grip index, which is highly beneficial for the production of high-performance passenger car tires. It could be observed that the improvements in rubber properties and tread performance were more obvious when the chloroacetate content of CNR was increased, probably due to the enhanced rubber-filler interaction, as demonstrated by the increased bound rubber content.

Use of hydrocarbon resins as an alternative to TDAE oil in tire tread compounds

The increasing demand on passenger car tires requires a continuous effort of tire manufacturers to improve their performance and safety. Achieving a balance between the three properties that form the “Magic Triangle of Tires” is one of the biggest challenges in this field. This work aims to improve this balance between wet grip, rolling and wear resistance by the use of performance hydrocarbon resins as an alternative to treated distillate aromatic extracted (TDAE) oil in tire tread compounds. In this framework, the effect on the in-rubber properties of five different hydrocarbon resins with different chemical nature, was studied in a styrene butadiene rubber (SBR)/polybutadiene rubber (BR) blend. The effect of the resins was analyzed by the use of different experimental techniques. All the compounds containing resin in their formulation, independently of their amount and chemical nature, showed an increase in the wet grip indicator and abrasion resistance indicator. However, it also was observed a deterioration in the rolling resistance indicator.

AGREEMENT BETWEEN FRICTION, ABRASION, AND ROLLING RESISTANCE IN SILICA-FILLED TIRE TREAD COMPOUNDS BY TUNING DEGREE OF SILANIZATION AND LOADING OF CARBON BLACK

ABSTRACT Development of green tires by using silica and silane in tread compounds has emerged as a key technology in the tire industry. One of the most important features of a green tire is its low rolling resistance; however, agreement between other performances of a tire, such as wet grip and wear, along with rolling resistance of tread compounds, is a serious challenge. Properties of tire tread compounds are very sensitive to the silanization of silica and the loading of primary and secondary fillers. This work investigates simultaneous effects of silanization of silica as the primary filler and loading of carbon black as the secondary filler. By performing dynamic-mechanical testing in strain sweep and mechanical testing of tire tread compounds, the degree of silanization of silica and loading of carbon black were tuned to make agreement between friction, abrasion, and rolling resistance of green tire tread compounds. Morphology of the filler, kinetics of vulcanization, and bound rubber content in the tread compounds were used to explain the findings. Other than dynamic-mechanical analyses to predict final performance of tread compounds, direct measurements of friction, abrasion, and rolling resistance of tread compounds showed a 43% increase in the coefficient of friction on wet concrete, a 47% increase in abrasion resistance, and a rolling resistance coefficient of approximately 6.5 by using 10 parts per hundred of rubber (phr) of bis(triethoxysilylpropyl)tetrasulfide and 10 phr of carbon black N330 as the secondary filler.

Enhancing silica dispersion and interfacial interaction in styrene butadiene/silica rubber composites by using epoxidized styrene butadiene rubber as interfacial compatibilizer

AbstractIt is usually desired but often challenging to improve the wet traction, and reduce the abrasion and rolling resistance simultaneously in tread rubber, which is referred to as “magic triangle” in tire industry. To fulfill this goal, the filler dispersion and interfacial interaction required to be improved, as they are two essential factors to concurrently govern the ultimate properties of rubber composites. Herein, we synthesized the epoxidized solution polymerized styrene butadiene rubber (ESSBR) with different epoxy level, and used them as interfacial compatibilizer to promote the silica dispersion and silica/rubber interfacial interaction. The epoxy of ESSBR would react with silanol on silica surface and co‐crosslink with SSBR simultaneously, therefore build a strong bridge between rubber matrix and filler. By incorporation of 20 phr of ESSBR‐15% (15% of double bonds on main chain was epoxidized), the wet grip was improved by 40%, and DIN abrasion and rolling resistance were reduced by 38% and 21%, respectively with hardly sacrifice the mechanical properties. We envisage that this study provides an approach for the fabrication of rubber composites with improved silica dispersion and strengthened interfacial interaction.

Preparation and mechanical properties of natural rubber composites reinforced by modified molybdenum disulfide

AbstractThe filler‐rubber interaction and filler dispersion in natural rubber (NR) composites are important factors in determining mechanical properties. Herein, Molybdenum disulfide (MoS2) and Al2O3‐coated MoS2 nanospheres are incorporated in NR/carbon black composites. The effects of MoS2 and Al2O3‐coated MoS2 on the morphology, thermal and mechanical properties of the NR composites are investigated. The morphology analysis indicates that Al2O3‐coated MoS2 could greatly improve the dispersion of carbon black in NR composites. MoS2 filler and carbon black show a synergetic effect on improving the properties of NR composites, leading to high abrasion resistance, tensile strength, elongation at break and expected dynamic mechanical properties. The thermal conductivity of NR composites increases with increasing the content of MoS2 and Al2O3‐coated MoS2. The thermal stability of the NR composites is also effectively improved by filling MoS2 and Al2O3‐coated MoS2. Furthermore, a small amount of Al2O3‐coated MoS2 significantly improves the abrasion resistance, wet grip and decreases rolling resistance of the composites. Al2O3‐coated MoS2 exhibits its potential application in green tires with good performance.

Effect of TESPT on viscoelastic and mechanical properties with the morphology of SSBR/BR hybrid nanocomposites

AbstractIn this study, the various properties of hybrid nanocomposite based on solution styrene butadiene rubber (SSBR)/butadiene rubber (BR) have been investigated. For this purpose, SSBR/BR rubber blend with nano‐silica and carbon black (CB) in constant filler content (60 phr) with and without Bis (triethoxysilylpropyl) tetrasulfide (TESPT) silane coupling agent was fabricated. The various properties, including curing behavior, morphology, dynamic–mechanical, and dissipation characteristics, were studied. For this objective, rheometry, field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), tensile test, and Dynamic mechanical thermal analysis (DMTA) were used. The results of rheometry illustrated that the addition of nano‐silica increased the optimum cure time (t90) and declined the cure rate index (CRI). However, the addition of surface‐modified silica improved the t90 and CRI. Replacing nano‐silica with CB also reduced the scorch and optimum cure time. TEM and SEM micrographs showed the good dispersion state of nano‐silica in the SSBR/BR/nano‐silica/TESPT matrix. According to the mechanical test data, including tensile, hardness, and abrasion, the addition of hybrid filler containing 40 phr modified nano‐silica and 20 phr CB improved properties. The results of DMTA illustrated the appropriate compatibility between blend phases, also an increase in the glass transition temperature (Tg) and storage modulus (E′) for the samples containing higher amounts of CB. Considering the importance of the damping factor at temperatures of −20, 0, and 60°C, which is related to ice grip, wet grip, and rolling resistance, respectively, the TSi40CB20 sample showed the essential properties of the magic triangle better than other samples. Dissipative properties also revealed that by increasing the filler content and replacing nano‐silica with CB, the dissipation of the compound increases significantly. According to the results, the optimum amount of nano‐silica and CB in the SSBR/BR/TESPT was 40 and 20 phr, respectively.

Multifunctional and anti-migration plasticizers based on bio-based phenol-functionalized liquid 1,2-polybutadiene

With the increasing demands for environmental friendliness, bio-based additives in rubber materials have attracted extensive research attention from the academy and industry. However, the low molecular weight and high polarity are detrimental to mixing compatibility with rubber materials. In this work, we prepare a phenol-functionalized 1,2-PB (1,2-PB-g-CA) by grafting bio-based cardanol onto 1,2-polybutadiene rubber (1,2-PB) based on the olefin metathesis. The 1,2-PB-g-CA demonstrate a controlled number average molecular weight from 7 × 103 to 4 × 104 and tuned functionality from 0% to 20%. The open reaction system exhibited a higher functionality due to the removal of small molecules. The 1,2-PB-g-CA was used as a plasticizer for silica filled styrene-butadiene rubber (SBR). The enhanced interfacial interaction between phenolic hydroxyl groups of cardanol and the silanol groups of silica significantly increased the compatibility of silica and rubber matrix. Compared with the common paraffinic oil, the obtained SBR/silica compounds were afforded low rolling resistance, high wet grip, and low heat build-up. Moreover, the 1,2-PB-g-CA showed better anti-migration properties. Therefore, our preparation method of bio-based modified liquid rubber has broad application prospects in high-performance “green tire.”

Tuning the low rolling resistance, wet grip, and heat build‐up properties of tyre tread formulations using carbon black/thermally exfoliated graphite hybrid fillers

AbstractEcofriendly green tyre tread compounds were developed with low rolling resistance, low heat buildup, and improved wet grip properties. A standard formulation of natural rubber (NR) and butadiene (BR) with 50 phr carbon black was prepared in a brabender plasticoder. Based on the processability, successful reduction of carbon black and aromatic oil content was done up to a minimum value of 32 and 3 phr respectively. Partial replacement of graphite with carbon black was done to achieve the optimized formulation. A binary filler system with 10 phr graphite and 22 phr carbon black was optimized based on the mechanical properties and further addition of graphite leads to reduction in properties due to agglomeration. To enhance the properties further, the graphite was thermally treated to get an exfoliated structure which can significantly improve the area of the filler/matrix macromolecules interface. This ultimately had a positive impact on targeted properties. A sudden thermal shock for 15 min at various temperatures ranging from 400 to 550°C was given and prepared the optimized binary formulation and evaluated the properties. Excellent results in terms of low rolling resistance (0.039) and heat build‐up (18°C) were recorded for final formulation. The flex fatigue resistance was enhanced and the thermal stability improved by 29°C.